Heat-sealable coated metal package and method of making same

ABSTRACT

A method of manufacturing a package which comprises; coating substantially all of one surface of a metal web or foil or sheet thickness with a homogenous coating of a heat sealable thermoplastic material having a lubricant constituent; applying said coating material in uniform thickness to at least one first elongated zone of metal web; simultaneously applying the coating material in a uniform thickness greater that the coating thickness in the first elongated zone disposed adjacent opposed transverse sides of the first zone; applying the coating by means of a gravure roll; providing a coating thickness in the second zone of about 0.75 to 4.0 lb./ream and providing a coating thickness in the first zone of about 0.30 to 2.0 lb./ream; and forming a package employing said coated metal web as a body component by heat sealing at least a portion of said second zone to a portion of said metal web or to another package component. A coated container body comprising a metal web provided with such two level coating; a first elongated zone of uniform coating thickness spaced inwardly for opposed transverse edges of the metal web; a second elongated zone of uniform coating thickness positioned intermediate each transverse edge of the metal web and the first elongated zone; the first zone having a width substantially greater than the second zone; and said metal web having at least one said second zone heat sealed to another portion of said metal web or to a separate package component to form said container body.

Jan. 1, 1974 F. E. MONKS 3,783,071

HEAT SEALABLE COATED METAL PACKAGE AND METHOD OF MAKING SAME OriginalFiled Oct. 5. 1969 FIG. I.

36 FIG. 3. 36 I Ax fi I l 1 1 as I38 1 -3a-- --3aaa as 40 L-40 l -40 I vi M, u l

INVENTOR.

FRANK E. MON/(S 12 20 MBM Attorney United States Patent Int. Cl. B05c1/16; B2911 23/10 US. Cl. 156217 17 Claims ABSTRACT OF THE DISCLOSURE Amethod of manufacturing a package which comprises: coating substantiallyall of one surface of a metal web of foil or sheet thickness with ahomogeneous coating of a heat scalable thermoplastic material having alubricant constituent; applying said coating material in uniformthickness to at least one first elongated zone of the metal Web;simultaneously applying the coating material in a uniform thicknessgreater than the coating thickness in the first elongated zone to atleast one elongated zone disposed adjacent opposed transverse sides ofthe first zone; applying the coating by means of a gravure roll;providing a coating thickness in the second zone of about 0.75 to 4.0lb./ream and providing a coating thickness in the first zone of about0.30 to 2.0 lb./ ream; and forming a package employing said coated metalweb as a body component by heat sealing at least a portion of saidsecond zone to a portion of said metal web or to another packagecomponent.

A coated container body comprising a metal web provided with such a twolevel coating; a first elongated zone of uniform coating thicknessspaced inwardly from opposed transverse edges of the metal web; a secondelongated zone of uniform coating thickness positioned intermediate eachtransverse edge of the metal web and the first elongated zone; the firstzone having a width substantially greater than the second zone; and saidmetal web having at least one said second zone heat sealed to anotherportion of said metal web or to a separate package component to formsaid container body.

CROSS-REFERENCE TO RELATED APPLICATION This is a continuation ofapplication Ser. No. 863,431, filed Oct. 3, 1969, now abandoned.

BACKGROUND OF THE INVENTION (a) Field of the invention This inventionrelates to a package or container comprising a metal web provided with aheat scalable thermoplastic, lubricating coating of two distinctthicknesses and a method of manufacturing the same.

(b) Description of the prior art stock are generally either heat sealedto each other in a lap seam joint, fin seam joint or folded-over finseamed. In the lap seam joint the inner surface adjacent one edge isadhesively secured to the outer surface adjacent the other edge. In thefin seam joints, inner surfaces adjacent each edge are adhesivelysecured to each other. Adjacent 3,783,071 Patented Jan. 1, 1974 edgesmay also be heat sealed to another portion of the container structure asin the taped butt seam joint systems. See US. Pats. 2,982,457, 3,183,802and 3,274,905.

In such systems, it has been conventional to provide a coating ofuniform thickness over the entire metal web. As greater coatingthickness is required for heat sealing than lubrication, this uniformthickness has been generally established on the basis of the need toequal or exceed the minimum thickness effective for heat sealingpurposes.

This uniformity of coating thickness while advantageous in terms ofsimplicity of coating procedure and effective functioning of the coatedmetal web when introduced into its final environment, be it a woundcontainer or other structure, does not provide for economicallyadvantageous use of coating materials. With economic considerations inpackaging materials becoming of increasing consequence, these factorshave become more meaningful.

SUMMARY OF THE INVENTION This invention provides a way of obtaining thedesired heat sealing and lubricating properties in a coated metal web,while obtaining meaningful economic benefits. In essence, the inventioncontemplates providing a homogeneous coating material which iscontinuously coated on a metal web. The coating thickness is varied inaccordance with the properties needed in a given zone of the metal.

The method of this invention contemplates applying the coating in auniform thickness to at least one first elongated zone of the metal web,which will generally be of sheet or foil thickness. Simultaneously, thecoating is applied in uniform thickness greater than that of the firstzone to at least two second zones. The coating material may be appliedby a gravure roll which provides the desired quantities of material tothe respective zones. When the metal web is to be employed as linerstock for a spirally or convolutely wound container body, the first zoneis positioned between a pair of second zones which are disposed adjacentthe transverse edges of the metal web. The coating thickness within thefirst zone is about 0.30 to 2.0 lb./ream and preferably about 0.30 to0.60 lb./ ream. In the second zone the coating thickness is about 0.75to 4.0 lb./ream and preferably about 0.75 to 1.5 lb./ ream.

The coated metal web of this invention is provided with a homogeneouscoating of a heat scalable thermoplastic material having a lubricantconstituent. The coating substantially continuously covers one surfaceof the metal Web. A first elongated zone of uniform coating thickness isspaced inwardly from the transverse edges of the metal web. A secondelongated zone of uniform coating thickness greater than the first zonecoating is disposed intermediate each transverse edge of the metal andthe first elongated zone. The first and second zones are parallel toeach other and are longitudinally substantially coextensive with themetal web. The first zone has a width substantially greater than eachsecond zone.

It is an object of this invention to provide a method of economicallycoating a metal web with a homogeneous coating material to providepredetermined variations in coating thickness in order to eliminatesuperfluous material from certain predetermined areas.

It is another object of this invention to provide a meth- 0d of coatingan elongated web of metal foil or sheet with a homogeneous coatingmaterial having both heat sealing and lubricating properties with theportions of the metal web intended to be heat sealed having a greatercoating thickness than other portions of the metal web.

It is another object of this invention to provide a method ofmanufacturing foil liner stock for use in the manufacture of spirally orconvolutely wound container bodies wherein adequate lubricant isprovided over the entire surface of the web and sufficient heat sealingmaterial is provided at the regions to be heat sealed.

It is yet another object of this invention to provide a coated elongatedmetal web which has been preferentially coated in at least two Zoneshaving different coating thicknesses but uniformly coated within anygiven zone.

These and other objects of the invention will be more fully understoodfrom the following description of the invention on reference to theillustrations appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic elevational viewillustrating a method of coating a metal web in accordance with thisinvention.

FIG. 2 is a transverse sectional elevation showing a web coated inaccordance with this invention oriented with the coated side up.

FIG. 3 shows a fragmentary plan view of a multiple width web coated inaccordance with this invention oriented with the coated side up.

FIG. 4 is a fragmentary sectional view showing a portion of a gravureroll overlying a metal web.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more specificallyto the drawings, in FIG. 1 there is shown one arrangement of apparatussuitable for use in the method of this invention. An elongated metal web2 is being unwound from reel 4 and passes through the bite of rolls 6,8. Roll 8 is a gravure roll which has a plurality of small cellscommunicating with the cylindrical surface thereof. As the roll 8 isrotated in the direction indicated, it enters coating material reservoir10 and coating material is received in the cells of roll 8. Continuedrotation of the roll causes the roll surface 12 to progressively passdoctor blade 14 which removes excess coating material and causes theexcess, under the influence of gravity, to return to the coatingmaterial reservoir 10. Back-up roll 6 maintains effective contactbetween roll surface 12 and web surface 16 in order to insure uniformcoating of the web as it progresses through the coating operation. Thecoated web may then be conveniently wound on a rewind roll for storageor may be transported directly to fabricating station.

In numerous uses, such as foil packaging, it is desired to establishstructural integrity of the final product by means of a heat sealobtained by means of the coating material. In addition, in numerous usessuch as in winding container bodies it is necessary to provide alubricated surface which will minimize frictional resistance and readilypass over the forming mandrel or other equipment. The coating materialemployed in this invention is a homogeneous heat scalable thermoplasticmaterial having a lubricant constituent. A vinyl or epoxy materialprovided with a slip coat additive may be employed with suitableresults.

I have determined that the coating thickness required for effectivelubrication is substantially less than the minimum coating thicknessrequired for effective heat seal bonding. Under conventional practice, auniform coating having a thickness not less than the minimum thicknessrequired for heat seal bonding would be provided over the entire metalweb. The method of this invention produces a coated metal web whichprovides zones of distinct coating thicknesses which correspond directlyto the functional needs of the particular metal web zone. Thus,referring to FIG. 2, it is seen that the metal web 20 is provided with afirst coating zone 22 having a first coating thickness suitable forproviding the desired lubricating properties. This coating thickness isuniform throughout the longitudinal extent of first zone 22. On eachopposed side of the first coating zone 22 is a second coating zone 24provided with a second coating thickness which is substantially thickerthan the coating thickness in first zone 22. Second zone 24 has acoating thickness which is at least as great as the minimum required foreffecting heat sealing of the material. While not illustrated, it willbe appreciated that additional zones of different coating thickness thanzones 22, 24 could be provided if desired.

The web shown in FIG. 2 would be suitable for use as liner stock in aspirally or convolutely wound container body. The full transverse widthof the web 20 is provided with an effective slip coating to permit readypassage over a mandrel. Also, second zone 24 provides sufiicientmaterial to permit heat sealing joinder either by way of lap seam or finseam to adjacent wraps of liner material or to a different member bymeans of a butt seam. All of this is accomplished while eliminating thequantity of coating material which would be present in void A were theweb 20 to have been coated throughout with a single coating of uniformthickness.

Referring now to FIG. 4, with more specific reference to the gravureroll 8, the structure employed to coat an article in the fashionillustrated in FIG. 2 is there shown. It is seen that the roll surface12 is provided with two series of cells or openings 30, 32 which areradially oriented within the roll 8 and communicate with surface 12.These cells are substantially uniformly positioned circumferentiallyabout the roll surface 12. The cells 30, 32, in the form shown, aregenerally radially oriented and hav a radially innermost portion whichis of paraboloid configurations and an outermost portion has a generallydiamond shaped transverse sectional configuration. It will beappreciated that other cell configurations may be effectively employed.The surface portions 12 intermediate adjacent cells are relativelynarrow with respect to the width of cells 30, 32 in order to provide foruniform gap free coating of the web.

It is seen that the cells 30 have substantially greater depth than thecells 32 and, therefore, will pick up a greater quantity of coatingmaterial from reservoir 10. As the coating material is released from therespective cells 30, 32, the portion of the web 20 underlying cells 30will receive a greater quantity of coating material and establish thecoating in second coating zone 24. The lesser quantity of coatingmaterial will be provided by cells 32 to first coating zone 22 in orderto establish that portion of the coating.

The gravure roll may be a steel roll provided with a chrome finish.While a copper finish might be employed, the chrome finish is moredurable and will resist the distortions resulting from roll wear. Whilein FIG. 4 the cells 30, 32 have been shown with capacity variationsrelated to cell depth, it will be appreciated that these capacityvariations could also be effected through variations in cell width, ifdesired.

In order to provide for effective performance of the coated metal web,while obtaining the desired economic benefits, the coating thicknesswithin the second zone 24 should be about 1.5 to 3 times that of thecoating thickness in the first zone 22. In general, the coatingthickness in the first zone is about 0.30 to 2.0 lb./ream and in thesecond zone is about 0.75 to 4.0 lb./ream. Below these ranges thelubricating and heat sealing properties, respectively, are notsufficient to provide the desired performance. Above these ranges thelimited advantages of any increase in desired properties is obtainedonly at a disproportionately high increase in cost of materials. In onepreferred form, the coating thickness within the first zone is about0.30 to 0.60 lb./ream (a ream is defined generally as 3,000 sq. ft. ofsurface area to be coated) and the coating within the second zone 24 isabout 0.75 to 1.5 lb./ream.

It will be appreciated that coating in accordance with this inventionneed not be applied to single widths of metal web. Multiple webs mightbe coated preferentially as provided for herein and ultimately slit intoindividual widths. Such an arrangement is illustrated generally in FIG.3, wherein web 34 is provided with a plurality of first coating zones 36and a plurality of second coating zones 38. The second coating zonesintermediate the transverse edges of web 34 are of double width.Severance of the web 34 along cutting lines 40 will produce sixindividual elongated webs of the type illustrated in FIG. 2.

Referring once more to FIG. 2, it is noted that the heat sealing zone24, in the form illustrated, is substantially narrower in transversewidth than the first coating zone 22, with the latter covering about 70to 98% of the transverse width of the metal web 20. For example, inliner stock having a first zone 22 with a width of about 4 to 6 inches,each second zone 24 might have a width of about /2 to V2 inch.

It will be appreciated that the metal web for most usages will have athickness within the sheet or foil classes. In a preferred form, themetal web is made of aluminum foil, having a thickness of about 0.00017to 0.0059 inch. This foil may or may not have its uncoated surfacesecured to one or more plies of back-up material. The coating materialwill cover substantially the entire useful portion of the metal web. Thetwo zones of varying thickness will in the form illustrated be orientedlongitudinally with respect to the elongated web and will be parallel toeach other as well as being substantially coextensive with the elongatedweb.

While for purposes of illustration, specific reference has been madeherein to the use of the coated metal web of this invention as linearmaterial for wound container bodies, it will be appreciated that theinvention in its more general aspects is not so limited. The inventionmay, for example, be advantageously employed in the manufacture of pouchtype packages from foil stock. As the method of fabricating a spirallywound container or pouch, apart from provision and use of the uniquecoating practices described hereinbefore, forms no part of the inventionper se, extended discussion of the same is deemed unnecessary. It willbe appreciated, however, that the invention may be employedadvantageously in a wide variety of conventional packages and methods ofmaking the same, as well as other desired package structures. In

the use of the metal web established by the practice of this invention,heat sealed joinder of at least a portion of the web to another portionthereof or to another package component will permit the advantageouspractice of the invention in fabricating the desired package in aneconomical fashion.

While for purposes of simplicity of illustration the invention has beendescribed with respect to a web provided with a multiple level coatinghaving elongated zones oriented with the elongated direction of the web,it will be appreciated that such zones may be transversely or angularlyoriented with respect to the elongated web. Also, by employingadditional coating steps one or more additional coatings may be providedat different orientations from the first multilevel coatings withrespect to the web. For example, after applying the coating shown inFIG. 4, portions of web 34 may be provided with additional zones of heatsealing thickness disposed transversely with respect to zones 38. Thismight be readily accomplished by means of a second gravure roll disposeddownstream of the first gravure roll. In this fashion various patternsof heat seal zones may be established, while retaining the economicbenefits of this invention in zones which are purely lucricating zones.

It will be appreciated that this invention provides a coated metal webadapted to function effectively with respect to the heat sealing andlubricating properties of its coating, while producing meaningfulsavings through reduced cost of coating material by means of specificpreferential coating thicknesses. All of this may be accomplished with asingle pass through the coating apparatus without the need for anysubsequent mechanical coating alteration. The coated sheet or foil maythen be employed in the same fashion as conventional coated materialemploying conventional equipment.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be apparent to those skilledin the art that numerous variations of the details may be made withoutdeparting from the invention as defined in the appended claims.

I claim: 1. A method of manufacturing a package, comprising providing anelongated metal web,

coating substantially all of one surface of said metal web with acontinuous homogeneous coating of a heat scalable thermoplastic materialhaving a lubricant constituent, applying said coating in uniformthickness to at least one first elongated zone of said metal web,simultaneously applying said coating in uniform thickness greater thanthe coating thickness in said first elongated zone to at least onesecond elongated zone, establishing at least one said second zoneimmediately adjacent and parallel to said first zone, said first zonebeing wider than each said second zone, said first and second zones eachbeing of substantially uniform width throughout their longitudinalextent, an forming a package employing said coated metal web as a bodycomponent by heat sealing at least a portion of said second zone to aportion of said metal web or to another package component. 2. The methodof claim 1 including applying coating material to several of said firstzones which are transversely spaced from each other, establishing saidsecond zones on opposed sides of each said first zone, and subsequentlylongitudinally slitting said metal web generally centrally of thetranverse width of at least one said second zone to provide a number ofcoated webs each having one said first coated zone. 3. The method ofclaim 2 including said metal web is aluminum having a thickness of about0.00017 to 0.0059 inch, and applying said coating material to only onesurface of said metal web and substantially completely coating saidsurface. 4. The method of claim 1 including establishing two said secondzones with said second zones disposed adjacent opposed transverse sidesof said first zone, applying said coating by means of a gravure rollwhich has cells of varying depth disposed in adjacent circumferentialbands on said roll to provide different quantities of said coatingmaterial to said first zone and said second zone, and applying coatingmaterial in said second zone in a thickness of about 1.5 to 3 times thatof said first zone. 5. The method of claim 4 including establishing eachsaid first zone with a coating thickness of about 0.30 to 0.60 lb./ream,establishing each said second zone with a coating thick ness of about0.75 to 1.5 lb./ream, and after applying said first and said second zonecoatings applying a third zone of coating to establish a coatingthickness of about 0.75 to 1.5 lb./ream disposed generally transverselywith respect to said first and second coating zones. 6. The method ofclaim 4 including folding said elongated metal web to superpose twoportions thereof with said second zones of one side generally alignedwith said second zones of said other side, and establishing a pouch byheat sealing said second zones of one said portion to said second zonesof the other said portion. 7. The method of claim 4 including windingsaid metal web over a mandrel to establish a liner of a compositecontainer by heat sealing one said second zone to an adjacent wrap ofsaid metal web or to an independent package component.

8. The method of claim 4 including establishing at least one third zonehaving a coating of uniform thickness greater than said first elongatedzone,

establishing said third zone generally perpendicular to said secondzone, and

establishing a pouch by heat sealing said second zones and said thirdzone to a superposed package defining web portion which is either aportion of said metal web or a separate metal web.

9. A coated metal container body comprising an elongated metal webhaving a first surface facing toward the container interior and a secondsurface facing toward the container exterior,

a homogeneous coating of a heat sealable thermoplastic material having alubricant constituent substantially continuously covering said firstsurface of said metal web,

a first elongated zone of uniform coating thickness disposed inwardlyfrom opposed transverse edges of said metal web,

a second elongated zone of uniform coating thickness greater than thethickness of said first elongated zone disposed intermediate eachtransverse edge of said metal web and said first elongated zone,

said first elongated zone of greater width than each said second zone,and

said metal web having at least one said second zone heat sealed toanother portion of said metal web or to a separate package component.

10. The package of claim 9 including said metal web folded to establisha pouch having a first portion of one said second zone heat sealed to anadjacent second portion of the same said second zone and a first portionof another said second zone heat sealed to an adjacent second portion ofthe said other second zone.

11. The package of claim 9 including said metal web being a liner of awound container with said second zone heat sealed to an adjacent wrap ofsaid metal web or to a separate package component.

12. The package of claim 9 including said package being a pouch formedby joinder of said first metal web to a second metal web,

said first metal web having at least one third zone having a coating ofuniform thickness greater than said first elongated zone,

said third zone disposed generally perpendicular to said second zone,and

said pouch having heat sealed joinder between said second and thirdzones and said second metal web.

13. The coated metal container body portion of claim 9 including saidmetal web is aluminum and has a thickness of about 0.00017 to 0.0059inch,

said coating in said first zone is of substantially uniform tranversewidth throughout its length,

said coating in said second zone is substantially uniform in widththroughout its length,

said first elongated zone has a coating thickness of about 0.30 to 0.60lb./ream,

said second elongated zone has a coating thickness of about 0.75 to 1.5lb./ream, and

said first and second zones are parallel to each other and substantiallylongitudinally coextensive with said metal web.

14. The coated metal contanier body portion of claim 13 including saidmetal web is adapted to serve as a liner material for a spirally woundcontainer,

each said second zone having a width of about A; to

/2 inch, and

said first zone having a width of about 4 to 6 inches.

15. The coated metal container body portion of claim 13 including 8 atleast one-third zone having a coating thickness of about 0.75 to 1.5lb./ream, and said third zone positioned generally tranversely withrespect to said first and second zones. 16. A method of manufacturing apackage, comprising:

providing an elongated metal web;

coating substantially all of one surface of said metal web with acontinuous homogeneous coating of a heat sealable thermoplastic materialhaving a lubricant constituent;

applying said coating in uniform thickness to at least one firstelongated zone of said metal web comprising from about to 98% of thetransverse width of said surface of said web;

simultaneously applying said coating to at least one second elongatedzone immediately adjacent and parallel to said first zone in uniformthickness of about 1.5 to 3 times the coating thickness in said firstelongated zone, said first and second zones each being of substantiallyuniform width throughout their longitudinal extent, and

forming a package employing said coated metal web as a body component byheat sealing at least a portion of said second zone to a portion of saidmetal web or to another package component.

17. A coated metal container body comprising:

an elongated aluminum metal web having a thickness of about 0.00017 to0.0059 inch, a first surface facing toward the container interior, and asecond surface facing toward the container exterior;

a homogeneous coating of a heat sealable thermoplastic material having alubricant constituent substantially continuously covering said firstsurface of said metal web;

a first elongated zone of substantially uniform transverse widththroughout its length and having a uniform coating thickness of about0.30 to 0.60 lb./ ream disposed inwardly from opposed tranverse edges ofsaid metal web, and covering about 70 to 98% of the transverse width ofsaid first surface of said metal web;

a second elongated zone of uniform coating thickness of about 0.75 to1.5 lb./ream and of substantially uniform width throughout its lengthdisposed intermediate each transverse edge of said metal web and saidfirst elongated zone, whereby said coating material provides aneffective slip coating over the entire surface of said web andsufiicient material within said second zones to effect a heat seal; and

said metal web having at least one said second zone heat sealed toanother portion of said metal web or to a separate package component toform said container body.

References Cited UNITED STATES PATENTS RALPH S. KENDALL, PrimaryExaminer 0 M. F. ESPOSITO, Assistant Examiner U.S. Cl. X.R.

